1. Field of the Invention
The present invention relates to a method for dividing and charging of non-azeotropic mixed refrigerant, by which on the occasion of successively dividing and charging a non-azeotropic mixed refrigerant filled in a refrigerant tank into a plurality of receivers, compositions of divided portions of the refrigerant are prevented from differing receiver from receiver.
2. Related Background Art
Conventional refrigerants for air-conditioning and refrigerating machines popularly used were those of single-component composition such as dichlorodifluoromethane (alias CFC12; note that aliases will also be used hereinafter) or chlorodifluoromethane (HCFC22). In recent years, however, depletion of the stratosphere's ozone layer due to chlorofluorocarbons (CFCs) was posed as a serious environmental problem and production thereof was stopped at the end of 1995. For the existing air-conditioning and refrigerating machines using the CFCs, mixed refrigerants comprised of a plurality of hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), fluorocarbons (FCs), hydrocarbons (HCs) or the like with adjusted physical properties and cooling performance were developed as alternatives or refills.
Further, the above-stated HCFCs have smaller effects on the depletion of the ozone layer than the CFCs, but, because of a high possibility of increase in amounts of use as alternatives to the CFCs, abolition of use of HCFCs in the year of 2020 was determined as a general rule and the international regulation of total quantity has been started since 1996. Refrigerants under research are thus those using HFC components with ozone depleting potential of zero that are not materials subject to the regulation, particularly as alternatives to HCFC 22 widely used for the air-conditioning machines and the like.
Since there is no single-component refrigerant capable of being used in the conventional machines for HCFC22 in place thereof as it is, HFC-based mixed refrigerants of two component system or three or more component system the physical properties of which were adjusted by mixing a plurality of components have been developed as refrigerant compositions capable of replacing HCFC22. From the same point of view, a variety of mixed refrigerants were proposed, for example, mixed refrigerants of plural HCs, mixed refrigerants of a HC with a HFC, and mixed refrigerants containing a hydrofluoroether (HFE) or a fluoroether (FE).
The most of these mixed refrigerants, however, are non-azeotropic mixed refrigerants, different from the single-component refrigerants such as CFC12 or HCFC22 and the azeotropic mixed refrigerants such as alias R502 having been used heretofore as low-temperature refrigerants. With such non-azeotropic mixed refrigerants, there was a problem that in successively dividing and charging the non-azeotropic mixed refrigerant from the refrigerant tank into a plurality of receivers, compositions of the respective receivers differed from the composition of original refrigerant (the original composition).
If the composition of refrigerant varied over the permissible limit in a receiver divisionally charged, the cooling performance and the other performance of air-conditioning or refrigerating machine would change out of utilization. In practice, the variation of composition becomes greater as an amount of residual refrigerant decreases in the refrigerant tank. In many cases, the residual refrigerant, for example after the draw of about 80% from the refrigerant tank, is thus not used for dividing and charging from the reason of the permissible limit of composition and it is returned to a charging factory as it is. The residual refrigerant returned to the charging factory, however, requires a lot of cost and time for recovery and recycling processes of refrigerant of varied composition, which is a cause of increase in the cost of refrigerant product.
As means for solving the problem of variation in the composition of liquid phase upon dividing and charging of non-azeotropic mixed refrigerant, for example, the bulletin of Japanese Laid-open Patent Application No. Hei 8-157810 and the International Laying-open Publication of WO 96/33377 present methods for preliminarily adjusting the composition of the refrigerant charged in the refrigerant tank so as to make a low-boiling-point component excessive. These methods are not, however, completely free of the variation of composition among the receivers depending upon the volume of the refrigerant tank, the quantity of draw, the number of dividing and charging processes, and so on.